Ferredoxin in the Phosphoroclastic Reaction of Pyruvic Acid and Its Relation to Nitrogen Fixation in Clostridium pasteurianum

We have reported recently that nitrogen fixation in cell extracts of Clostriclium pasteurianum is dependent upon transitory intermediates from pyruvate metabolism (l-3). Thus, fixation has been observed to occur only while pyruvate is being actively consumed; the mole ratio of pyruvate consumed to Nz fixed approximated 100 : 1. Except for Z-ketobutyrate, no replacement for pyruvate has been found among many compounds and combinations tested. The predominant pathway of pyruvate utilization in these extracts involves oxidative decarboxylation by the so-called phosphoroclastic reaction.